I think you were too fast but too slow
They were my test images; then I deleted them. Once an image is deleted the image ID (plus613.net/image/12345) isn't reused; just disabled and displays a random image forevermore. You probably loaded the gallery before I'd deleted them, but clicked the images afterwards perhaps?
Let me know if you can still see those pictures. That's my bigger worry. I've been messing with some code tonight and doing some testing.